The subject matter disclosed herein relates to gas turbines, and more particularly to cooling a turbine casing.
Gas turbines generally combust a fuel/oxidant mixture to generate hot combustion gases, which pass through one or more turbine stages of a turbine section. The hot combustion gases drive turbine blades to rotate within a surrounding casing assembly, thereby driving rotation of a turbine shaft. The casing assembly may include inner and outer shells, shrouds, joints, or other structures. In general, the hot combustion gases cause thermal expansion of structures in the turbine section, such as the shells, shrouds, or joints. This thermal expansion can complicate the design of gas turbines, because thermal expansion can cause changes in the clearance between the blades and the casing assembly. Accordingly, improvements to the design of gas turbines may be helpful to control the clearance during thermal expansion, and to minimize any variations in the roundness of gas turbine components, such as the casing assembly.